Oct 31, 2025 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

Exposure Dose Distribution of the Workers at Fukushima Daiichi Nuclear Power Station

Updated on 31 Oct 2025

Radiation Exposure Dose Distributions

(1)The distribution of external exposure dose of the workers during the last 3 months
(Numbers of workers who entered each area every month)
Effective dose (E) mSv	July-2025			August-2025			September-2025
Effective dose (E) mSv	TEPCO	Contractors	Total	TEPCO	Contractors	Total	TEPCO	Contractors	Total
100<E	0	0	0	0	0	0	0	0	0
75<E≤100	0	0	0	0	0	0	0	0	0
50<E≤75	0	0	0	0	0	0	0	0	0
20<E≤50	0	0	0	0	0	0	0	0	0
10<E≤20	0	0	0	0	0	0	0	1	1
5<E≤10	0	16	16	0	43	43	0	45	45
1<E≤5	9	424	433	1	318	319	8	349	357
E≤1	927	6381	7308	1038	6347	7385	985	6447	7432
Total	936	6821	7757	1039	6708	7747	993	6842	7835
Maximum(mSv)	2.10	7.50	7.50	1.30	8.40	8.40	1.66	10.50	10.50
Average(mSv)	0.06	0.24	0.22	0.03	0.22	0.20	0.06	0.24	0.22

(*)Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).

(2)Combined Cumulative Effective Dose from April 2021 (Internal and External)
Effective dose (E) mSv	April 2021 - August 2025			April 2021 - September 2025			Difference
Effective dose (E) mSv	TEPCO	Contractors	Total	TEPCO	Contractors	Total	TEPCO	Contractors	Total
100<E	0	0	0	0	0	0	0	0	0
75<E≤100	0	0	0	0	1	1	0	1	1
50<E≤75	0	158	158	0	165	165	0	7	7
20<E≤50	39	1496	1535	39	1531	1570	0	35	35
10<E≤20	77	1989	2066	79	2002	2081	2	13	15
5<E≤10	142	1826	1968	149	1833	1982	7	7	14
1<E≤5	388	2972	3360	383	2977	3360	-5	5	0
E≤1	1411	9578	10989	1417	9676	11093	6	98	104
Total	2057	18019	20076	2067	18185	20252	10	166	176
Maximum(mSv)	39.52	74.62	74.62	39.52	75.33	75.33	-	-	-
Average(mSv)	2.10	5.81	5.43	2.12	5.84	5.46	-	-	-

(*) Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).

(3) Combined Cumulative Effective Dose from April 2025
Effective dose (E) mSv	April 2025 - August 2025			April 2025 - September 2025			Difference
Effective dose (E) mSv	TEPCO	Contractors	Total	TEPCO	Contractors	Total	TEPCO	Contractors	Total
100<E	0	0	0	0	0	0	0	0	0
75<E≤100	0	0	0	0	0	0	0	0	0
50<E≤75	0	0	0	0	0	0	0	0	0
20<E≤50	0	0	0	0	0	0	0	0	0
10<E≤20	0	95	95	0	176	176	0	81	81
5<E≤10	1	378	379	2	436	438	1	58	59
1<E≤5	71	1276	1347	96	1423	1519	25	147	172
E≤1	1267	6681	7948	1264	6692	7956	-3	11	8
Total	1339	8430	9769	1362	8727	10089	23	297	320
Maximum(mSv)	5.80	14.40	14.40	5.85	15.47	15.47	-	-	-
Average(mSv)	0.19	0.95	0.85	0.23	1.11	0.99	-	-	-

(*): Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).

(4) Distribution of sum of external exposure dose and internal exposure dose of workers engaged in specified high-dose work (Effective Dose)
Effective dose (E) mSv	March 2011- September 2015
100<E	1
75<E≤100	191
50<E≤75	233
20<E≤50	267
10<E≤20	186
5<E≤10	129
1<E≤5	145
E≤1	51
Total	1203
Maximum(mSv)	102.69
Average(mSv)	36.49

(As specified high-dose work has not been performed since October 2015, the table shows the data up to September 2015.)

(*): Workers engaged in work to which dose limit (100 mSv) during emergency work is applied in line with Article 7 of the Ordinance on Prevention of Ionizing Radiation Hazards.
Specifically, these workers are those who are engaged in work to maintain the functions of a nuclear reactor facility or spent fuel storage pool, or in work to maintain functions to suppress or prevent the possible release of a large amount of radioactive materials due to a failure of or damage to the nuclear reactor facility at a location around the nuclear reactor facility, steam turbine, or accessory facility where hourly dose may exceed 0.1 mSv.
It should be noted that only TEPCO employees have so far been engaged in specified high-dose work.
(*): The number of workers engaged in specified high-dose work is that of workers who were registered as such at least once during the period between March 2011 and September 2015.
(*): Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).
(*): The results of re-evaluating committed doses in March 2011 reveal that maximum cumulative effective doses for the period between March 2011 and September 2015 exceeded 100.